1. Field of the Invention
The present invention relates to an ink jet recording apparatus and a recovery method thereof, and more particularly to an ink jet recording apparatus for performing the color recording and a recovery method thereof.
2. Related Background Art
The ink jet recording apparatuses are typically provided with a variety of mechanisms for maintaining the ink discharge condition excellent by preventing the viscosity of ink from increasing due to evaporation of water content of the ink at or around discharge ports where the ink makes contact with the air, or removing viscous ink or bubbles produced.
Therefore, this type of ink jet recording apparatus is provided with a capping mechanism for preventing evaporation of water content of the ink from the discharge ports by sealably enclosing (or capping) the face where the discharge ports of the recording head are provided while the recording is not performed to discharge ink droplets.
Also, in order to effect the stabler ink discharge, a so-called xe2x80x9cpredischargexe2x80x9d is conducted to renew the ink in the discharge ports not particularly involving recording by discharging the ink from all the discharge ports or the desired discharge ports of the recording head at a predetermined location periodically, such as during the recording operation, or the ink suction or ink pressurization is performed to expel the thickened ink or produced bubbles by sucking the ink on and within the discharge ports at the start of recording or at every desired time interval.
FIG. 36 is a perspective view illustrating the construction of a main portion of a conventional ink jet recording apparatus.
In FIG. 36, 921 is an ink jet recording cartridge (hereinafter simply referred to as a cartridge) integrally comprising a recording head having a nozzle portion for jetting the ink mounted on a carriage 922 and an ink supply unit having an ink tank for storing the ink and a supply passageway.
This cartridge 921 is detachably secured to the carriage 922 to use either a cartridge dedicated for Bk (black) ink recording or a cartridge dedicated for color ink recording by replacement. The carriage 922 and the cartridge 921 is electrically connected to a contact pad, not shown. 923 is an electrical substrate for controlling the ink discharge from the cartridge 921, and 924 is a flexible cable for connecting the electrical substrate 923 to the carriage 922. 925 is a sheet feeding motor, in which the recording sheet P can be conveyed in a direction of the arrow f as shown by a pair of rollers 926 by the driving of this sheet feeding motor 925. 927 is a roller for regulating the recording sheet P flat in cooperation with the rollers 926 and forming the recording plane for the recording cartridge 921.
928 is a carriage driving belt connected to the carriage 922, 929 is a motor for driving that belt in a direction of S as shown, and 930 is a pair of guide rails for the carriage 922. The carriage 922 is moved along the guide rails 930 in the direction of S as shown by the driving of the motor 929 to effect the recording on the recording plane.
The cartridge 921 is mounted on the carriage 922, which is driven along the recording sheet P in the direction of S as shown in FIG. 36 by the motor 929. The recording sheet P is conveyed in a direction of the arrow f as shown via the roller 927 by the driving of the sheet feeding motor 925. Thereby, the two-dimensional scanning by the recording head 921 can be effected. Then, the recording head 921 can perform the recording on the recording sheet P by jetting ink droplets under control of a control unit.
931 is a recovery device, opposed to the recording cartridge 921, for effecting the recovery operation of the recording cartridge 921 at a home position H of the recording cartridge 921. The recovery device 931 is comprised of a predischarge receiving portion 1311 for capturing ink droplets discharged at the predischarge as previously described to lead them to an ink reservoir (not shown), a wiping blade 1312 for wiping out ink droplets or foreign matter such as paper powder adhering to the discharge port face of recording head, and capping means 1313 having a cap for enclosing the discharge port face of recording head when the recording operation is not performed, or in the suction recovery operation.
The wiping blade 1312 and capping means 1313 are disposed movable back and forth with respect to the cartridge 921, and is capable of wiping or capping the discharge port face at desired timings. Also, capping means is connected to a suction pump (not shown) via a tube to be able to produce a negative pressure within the cap at desired timings.
A flowchart exemplifying a sequence of suction recovery operation in the recovery device as above constructed is shown in FIG. 37. If the suction recovery operation is instructed, the carriage 922 is moved to a home position (HP) (step S701), and the capping means covers the discharge port face to complete the capping (step S702). Next, the suction pump is activated to produce a negative pressure within the cap to suck the ink from the discharge ports to effect the suction operation, until the suction operation is completed by stopping the activation of suction pump at a predetermined timing (step S703).
Then, the cap in the capping means is separated away from the discharge port face, so that the interior of the cap is in communication with the atmosphere (step S704). Then, the suction pump is activated again to remove the ink within the pump, the tube and the cap (step S705). Then, the wiping blade advance to the discharge port face (step S706), and further the carriage 22 is moved in a direction toward the blade to allow the wiping blade to rub against the discharge port face to effect wiping to remove the ink adhering to the discharge port face (step S707).
Further, the carriage 922 continues to be moved in the same direction, and executes the predischarge upon reaching a position at which the discharge ports are opposed to the predischarge receiving portion, to expel the unnecessary ink or small bubbles out of the nozzles (step S708). By the suction recovery comprising such a series or a repetition of operations, the filling of the ink into the discharge ports, the removal of bubbles or unnecessary ink out of the ink flow passages, or the removal of foreign matter on the discharge port face, can be effectively made.
However, in recent years, the recording heads allows the discharge ports and the liquid channels in communication with them to be constructed quite finely and at high density, for which the prior suction recovery methods as heretofore used have become less effective in some cases.
FIGS. 38A and 38B are schematic views illustrating how the ink within liquid passageway is parted into a plurality of sections, as an example of the above cases. FIG. 38A is a typical view showing the constitution of cartridge 921, and FIG. 38B is a cross-sectional view of cartridge 921 taken along a plane V including an array of discharge ports, representing an ink filled state.
In FIG. 38A, 811 are nozzles each of which at the end is an ink discharge port, and internally provided with driving means for discharging each of the inks. 812 is a liquid chamber commonly provided to each nozzle (referred to as a common liquid chamber), and 813 is an ink flow passageway for connecting an absorbing member 814 containing the ink to the common liquid chamber 812.
In FIG. 38B, the solid painted portion indicates the ink filled state, wherein the ink is parted into four sections 813a, 813b, 813c, 813d in the figure.
With such a head in the ink filled state, it is impossible to continue the printing, for which the suction recovery is needed. FIG. 39 is a typical view showing the state of a head cartridge at the time of starting the suction. 1313 is capping means as previously described to produce a negative pressure P0 within the cap. However, since the ink is filled within the nozzles and the common liquid chamber 812, the negative pressure reached at an adjoining gap is negative pressure P1 smaller than P0 due to a pressure loss caused by the resistance between the nozzle/common liquid chamber inner wall surface and the ink.
At a further adjoining gap is reached only a negative pressure P2 further smaller than the negative pressure P1 due to a pressure loss caused by the resistance of an ink region 813a with the flow passage wall. By repeating this, it follows that a negative pressure P4 reached at a gap in the junction between the absorbing member 814 which is an ink supply unit and the flow passage is significantly smaller than the negative pressure P0 within the cap. To effect the suction, this negative pressure P4 must exceed the ink holding force of the absorbing member, and below it, the ink can not be filled even if the conventional suction recovery operation is repeated many times.
Conventionally, in order to avoid such an ink unfilled state, some considerations have been taken, including:
(a) Setting the suction negative pressure/suction amount large enough
(b) Enlarging sufficiently the cross section of flow passage to reduce the pressure loss
(c) Shortening sufficiently the length of flow passage to reduce the number of parted portions. However, in the case of (a), there are some problems including the increased waste ink, or the larger pump, and in the case of (b), there are similar problems such as the increased necessary suction amount caused by the increased flow passage volume, which impeded the fabrication of an ink jet recording apparatus of small size, and with low running costs. Also, in the case of (c), the vibration due to ink flow within the ink absorbing member 814 and the supply passage affects the inside of the nozzles, and is more likely to cause a discharge failure, resulting in a problem of impeding the fast and high quality recording.
Furthermore, as the recent trends, there have been remarkable progresses in the respects of:
A. Finer nozzles intended to increase the recording resolution
B. Lower surface tension of the ink intended to enhance the ink drying rate,
wherein owing to the increased pressure loss in the case of A, or the increased bubble production frequency in the case of B, the problem of the ink unfilled state caused by the ink split has become increasingly more important.
As above described, in the conventional suction recovery methods, it was difficult to construct an ink jet recording apparatus having small size, low operating costs, high speeds, higher quality, high resolution recording, and high rate fixing, while avoiding or resolving the ink unfilled state due to ink split.
The conventional suction recovery means for stabilizing the ink discharge for use with the ink jet recording apparatus as above described involves making a simple suction operation with one peak of suction negative pressure by placing a cap made of an elastic material such as rubber into close contact with the ink jet recording head having a number of ink discharge ports to cover the discharge ports, and reducing the pressure within cap by means of a suction pump.
However, where the ink can not be discharged due to bank of bubbles in the ink supply passage, common liquid chamber and liquid channels provided with discharging heaters within the recording head, or where the ink can not be discharged due to broken meniscus of the ink discharge port, the ink residing within the recording head may be drawn back to the ink tank, with some bubbles left on the wall surface, owing to a negative pressure (capillary force) of the absorbing member holding the ink.
With such suction recovery means having an operation mode in which the peak of suction negative pressure occurs once when the ink is in the undischarged condition, if the suction negative pressure is set low enough not draw bubbles together with the ink from the ink tank containing the absorbing member holding the ink, bubbles already residing within the recording head can not be removed, while if the suction negative pressure is set high enough to be able to remove bubbles already residing within the recording head, the negative pressure (capillary force) of the absorbing member holding the ink and the suction negative pressure becomes unbalanced to draw bubbles together with the ink, possibly resulting in a print failure such as undischarged due to bubbles.
In particular, in an ink jet unit of the recording head/ink tank integral type in which an ink tank is replaceable, because of poor contact between the absorbing member holding the ink and the filter in the ink tank immediately after replacing the ink tank, bubbles are taken inform the ink tank into the ink supply passage, the common liquid chamber and the liquid channels provided with the discharging heaters within the recording head, if the suction negative pressure is high. Also, as the ink remain within the ink tank decreases, the negative pressure (capillary force) at which the ink tank holds the ink increases, and is unbalanced with the suction negative pressure to easily draw bubbles together with the ink to cause such bubbles to be brought into the recording head. In this way, in the condition where numerous bubbles exist within the recording head, when a new ink tank having a great amount of ink remain is attached, it is difficult to remove bubbles within the recording head without taking in bubbles from the ink tank, with suction recovery means involving suction operation where one peak of suction negative pressure occurs, easily bringing about a print failure such as undischarged due to bubbles.
Also, in an ink jet unit having a color recording head in which a plurality of discharge ports through which different color inks can be discharged within the same head are arranged on the same plane or straight line, and a plurality of ink tanks storing different color inks to be supplied to the color recording head, the plurality of discharge ports with different color inks are subjected to suction recovery simultaneously with one suction cap made of elastic material such as rubber. Therefore, if the suction operation where the peak of suction negative pressure occurs once, set at a high suction negative pressure to allow removal of bubbles successfully, was performed, with an ink tank having greater ink consumption, the absorbing member holding the ink had increased negative pressure (capillary force), so that the mixed inks of different colors expelled into the cap when a simple suction operation was conducted flowed back through the ink discharge ports into the liquid channels and the common liquid chamber, further into the ink supply passage, resulting in significant color mixture in some instances. To resolve this color mixture, the predischarge, if conducted, may take large amounts of discharged ink and the time.
In the field of ink jet recording, in recent years, the ink jet units of the cartridge form in which a recording head and an ink tank are integrated have been utilized from the standpoints of smaller apparatus and maintenance free. Such an ink jet unit is detachably mounted on a scanning carriage provided in the recording apparatus, and if the ink in the ink tank is used up, the user can simply replace it with a new ink jet unit.
In recent years, however, the demands for the color image have been raised, and to satisfy the demands for the coloration by the ink jet unit as above described, there have appeared, for performing the color recording, an arrangement having the ink jet units for colors in parallel along a scanning direction on the carriage, and an arrangement having a color ink jet unit in which an ink tank for storing the inks of yellow, magenta and cyan and a head for discharging these inks are integrally disposed in parallel, and a separate ink jet unit for the black alone disposed on the carriage, for example.
Particularly, the apparatuses using a recording head of integral type of mounting a color head cartridge containing yellow, magenta, cyan and black inks have been proposed, but none of them have not been put to practical use, and the color head cartridge that has been practically used is simply of such a construction that a recording head cartridge for three colors of yellow, magenta and cyan (hereinafter Y, M, C) integrally, and a black (hereinafter BK) recording head cartridge are replaceably provided, and the recording is performed with either one on the carriage. Further, with such apparatus practically used, no suction recovery operation is performed upon replacement of the head cartridge.
Furthermore, the above color head cartridge has an ink tank for three color of Y, M and C integrally, and if the ink is used up, the head cartridge itself must be replaced.
In detachably mounting the color head cartridge of integral type for Y, M and C, or the BK head cartridge which is replaceable with each other on the recording apparatus main body, the suction recovery operation should be carried out to provided superior image reliability and stability. However, the suction recovery operation, if performed under the same conditions for the color head cartridge of integral type for Y, M, C or Y, M, C, BK and the BK head cartridge, will result in wasteful consumption of the ink, because the maximum recovery condition must be employed in both cases.
And it has been found that because of the use of the color head unit, it is difficult to prevent degradation or disorder of the printed image owing to color mixture between color nozzles.
It is an object of the present invention to provide an ink jet recording apparatus and a recovery method thereof, in which a plurality of different heads can be replaced and freely mounted or demounted, and wherein the recovery operation or the suction condition for the ink jet recording apparatus is made different from each other, while the color mixture between color nozzles in a color head unit can be prevented.
To accomplish such an object, the present invention provides an ink jet recording apparatus in which a plurality of types of heads or head cartridges can be replaced on the replacement position set along a main scan direction in the recording apparatus having a recording head detachably mounted at a predetermined position on a carriage, wherein a head, upon being mounted, is brought into contact with an electrical contact face provided on the carriage to identify the plurality of types of heads which are each provided with an ID of its own for the identification of head type, thereby setting the recovery condition or the suction condition in accordance with the head type as identified.
If the BK head cartridge is identified, the recovery condition I is selected to perform the suction operation, wiping operation, and predischarge corresponding to BK. Then, if the color head cartridge is detected to be mounted, the recovery condition II is selected to perform the color suction operation, wiping and color predischarge (for prevention of color mixture).
Also, if the color head cartridge is detected and further the replacement of ink tank is detected or predicted, the recovery condition III is selected to perform the tank replacement suction operation, color suction operation, wiping and color predischarge (for prevention of color mixture) for the optimization.
Thus, according to the present invention, the type of head or head cartridge is automatically discriminated to optimize the recovery operation, and thus prevent the wasteful ink consumption due to suction operation, or the color mixture of the color head, whereby the reliable and stable ink discharge can be effected.
It is another object of the present invention to provide an ink jet recording apparatus and a recovery method thereof which can secure the enough supply of the ink to the discharge ports by eliminating the ink unfilled state caused by the ink split.
To accomplish such an object, the present invention provides an ink jet recording apparatus comprising ink discharge means for discharging the ink to make the image recording, and suction means having a cap and a suction pump for sucking the ink within this ink discharge means to expel it outside, wherein there is provided a prior-to-suction predischarge recovery mode of operating said suction means after discharging the ink to the non-image area.
According to the present invention, an ink jet recording apparatus having an effective recovery method to resolve the ink split state can be constructed, whereby the ink jet recording apparatus can be made smaller and has low running costs, and can effect the fast, high quality and high resolution recording, with the fast fixing.
It is a further object of the present invention to provide an ink jet recording apparatus having an ink jet unit of the recording head/ink tank integral type in which an ink tank can be replaced, wherein bubbles can be extinguished from an ink supply passage, a common liquid chamber, and the liquid channels in which discharging heaters are provided, and wherein the ink jet unit comprising a color recording head having a plurality of discharge ports capable of discharging different color inks from the same head arranged on the same plane or straight line, and a plurality of ink tanks for storing different color inks to be supplied to the color recording head is provided with suction recovery means for preventing the color mixture after suction to always effect the stable recording without having a print failure.
Such ink jet recording apparatus of the present invention comprises a recording head having the discharge ports for discharging the ink, an ink tank for storing the ink to be supplied to the recording head, and suction recovery means for stabilizing the ink discharge from the recording head, characterized in that said suction recovery means has a plurality of suction operations, which can be selected in accordance with the content of the discharge stabilization.
Also, the ink jet recording apparatus of the present invention comprises a color recording head having a plurality of discharge ports capable of discharging different color inks arranged on the same plane or straight line, a plurality of ink tanks for storing the inks of different colors to be supplied to said color recording head, and suction recovery means for stabilizing the ink discharge from said color recording head with only one cap provided for the suction, characterized in that said suction recovery means makes the suction in such a way as to divide the motion of piston stroke in the suction operation into plural sections to intermittently perform the operation.
In the present invention, a plurality of suction operations in the suction recovery means should be made at different pressures in sucking the ink from the discharge ports, and it is more effective to perform two or more different types of suction operations consecutively. Furthermore, the suction operation is desirably continuously switched in succession from higher suction pressure to lower suction pressure, and preferably in accordance with the ink remain within the ink tank.
And in an ink jet unit having a color recording head having a plurality of discharge ports capable of discharging different color inks arranged on the same plane or straight line, and a plurality of ink tanks for storing different color inks to be supplied to the color recording head, the suction operation of the suction recovery means should be changed in accordance with the state of each color, and it is desirable to set the suction operation of suction recovery means with the minimum ink remain among the ink tanks for multiple colors.
In an ink jet recording apparatus using an ink jet unit of the recording head/ink tank integral type in which the recording head and the ink tank can be replaced at will, the use of said suction recovery means is very effective.